title: Frozen-thawed embryo transfer cycles: clinical outcomes of single and double blastocyst transfers.
abstract: OBJECTIVE
  To evaluate clinical outcomes of frozen-thawed embryo transfer cycles when one or two blastocysts are transferred.
  
  
  METHODS
  Retrospective chart review
  
  
  RESULTS
  Two hundred forty-three frozen blastocyst transfer (FBT) cycles were analyzed. Clinical pregnancy rate (50.4% vs. 34.7%), live birth rate (45.8% vs. 30.6%), and twin live birth rate (19.3% vs. 0) were significantly higher in the double versus single FBT group, respectively (p < 0.05). Prior fresh cycle success with same-cohort embryos did not predict outcome of FBT cycle. When the fresh cycle was unsuccessful, there still was a significant increase in twinning when two frozen-thawed blastocysts were transferred.
  
  
  CONCLUSIONS
  Transferring two blastocysts during an FBT cycle resulted in higher live birth and twin live birth rates. Single FBT provided acceptable pregnancy rates for couples seeking to avoid a multiple pregnancy or for those having a single blastocyst stored. Interestingly, the outcome of fresh cycle with same-cohort embryos did not influence the outcome of frozen-thawed cycle.
authors.affiliation: Vincent Obstetrics and Gynecology Service, Division of Reproductive Medicine and IVF, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. inna_berin@yahoo.com
authors.forename: Inna
authors.initials: I
authors.lastname: Berin
authors.forename: Sarah T
authors.initials: ST
authors.lastname: McLellan
authors.forename: Eric A
authors.initials: EA
authors.lastname: Macklin
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Toth
authors.forename: Diane L
authors.initials: DL
authors.lastname: Wright
mesh_terms: D015331:Cohort Studies; D015925:Cryopreservation; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D012189:Retrospective Studies; D014427:Twins